Recently, liquid crystal displays (LCD) have been widely applied in electrical products due to the rapid progress of optical technology and semiconductor technology. Moreover, with advantages of high image quality, compact size, light weight, low driving voltage and low power consumption, LCDs have been introduced into portable computers, personal digital assistants and color televisions, and have become the mainstream display apparatus.
FIG. 1 shows a diagram of a conventional source driver 100 of the LCD. The source driver 100 includes channels (108,110), a multiplexer 112, output pads (114,116), a databus 118 and a charge sharing switch 120. The channels 108 and 110 are connected to the output pads 114 and 116, respectively, via the multiplexer 112. The charge sharing switch 120 is electrically connected between the output pads 114 and 116 to share the voltages on the outputs if needed. Each channel has a shift register (122 or 132), a latch unit (123 or 133), a level shifter (128 or 138) and a digital-to-analog converter (DAC) (130 or 140). Each latch unit comprises a first latch (124 or 134) and a second latch (126 or 136) connected in series. The data is transmitted on the data bus 118 and stored in the latch units, and moreover, the data is stored first in the first latch and then stored in the second latch. The data is further sent to a display (not shown) via the output pads 114 and 116 to show corresponding images on the display.
However, when the power supply powering the source driver is being turned off, the power supplying to the source driver decreases and the channels may malfunction owing to the power insufficient, which results in abnormal images, such as line defects or band mura, shown on the display.